Double-Checking is a Sunnah (Hadith No. 1276)
Narrated Abu Humaid Al-Sa’idi (radiallaahu `anhu):
Allah’s Apostle (sallallaahu `alayhi wasallam) appointed a man called Ibn Al-Lutbiya, from the tribe of Al-Asd to collect Zakat from Bani Sulaim. When he returned, (after collecting the Zakat) the Prophet (sallallaahu `alayhi wasallam) checked the account with him.
So double check whatever it is that you assign to someone. Especially money matters. It’s a Sunnah!